California's aquifers are being drained as we speak. Parts of the central valley have subsided more than 10 meters as the farmers pumped the underlying aquifer dry. Aquifers are the most efficient way of storing water- no evaporation!
Given the above, it would seem best to operate desal plants 24x7x365, rain or shine, and pump the resulting potable water directly into the aquifers until full. I'll suggest a backronym free of charge: the California Aquifer Restoration Project (CARP).